1. Field of the Invention
The present invention relates to a liquid ejection device such as a drug ejection device which ejects a drug to be inhaled through a respiratory system of a human body. The present invention particularly relates to a technology of allowing a user to inhale an ejected liquid more reliably in a liquid ejection device for health care adapted so as to be portably owned by the user.
2. Description of the Related Art
In recent years, owing to development in medicine and science, the average life span has become long and we are entering an aging society. On the other hand, change in eating habits and living environment, and environmental pollution are accelerated. New diseases and infection diseases by viruses and germs have been found. Therefore, people feel increased anxiety about health. Especially in the countries called developed countries, an increase in the number of patients of the diseases caused by lifestyle habits such as diabetes and hypertension has become the problem.
Meanwhile, the number of medical institutions does not increase to such an extent as to cope with such increase in the number of patients, and some areas have no medical institution available for ambulant patients. Therefore, the future countermeasure including policies has become a matter of concern.
Describing with a concrete example, of the patients of diabetes on the increase at present, the patients of insulin-dependent diabetes mellitus called I type do not have insulin secreted from their pancreas. Therefore, they need to be regularly given insulin. Administration of insulin is performed by hypodermic injection at present, and therefore, it gives a large physical and mental burden on the users.
In order to reduce such a burden on the users, a pen type injector which has a fine needle and gives less pain has been developed. However, since the patients of I type diabetes live in the same manner as normal healthy people except that they needs to have regular administration of insulin, they are mentally reluctant to have injection in public even with a pen type injector. Therefore, administration at a proper time is difficult.
As a result, such a method brings about the possibility that proper treatment for the users is not performed. However, by a drug ejection device which allows the users to take a drug by inhalation, treatment for the users who can utilize an information database such as electronic medical records is being materialized. Such a drug ejection device has a storage unit which stores information relating to the individual users including the medical records and the information of the prescription of the users. The drug ejection device also has an ejection control unit which is a portable terminal also having the function of the inhalator device that ejects a drug as minute droplets to be inhaled by a user, and also controls the inhalator device according to an air intake profile to allow the inhalator to eject the drug so that the user can inhale the drug according to the information of the prescription.
Such a drug ejection device can accurately manage the dosage and administration interval of the drug according to the prescription, and conducts proper ejection control according to the air intake profile of the individual users. Therefore, the drug ejection device can efficiently give the drug. According to this, the medical appliance such as an injector does not need to be used on the occasion of administration of a drug as in the conventional method. Therefore, it is known that not only the operation can be easily made without expert knowledge, but also pain to the users caused by injection needles can be eliminated (see WO 1995/001137, WO 2002/004043).
On one hand, about the reliability and proper operation of the drug ejection device, a burden is likely to be imposed on the users. For example, when the user suffers a chronic disease and needs to be given a drug regularly, administration and management of the drug are left to the reliability of the drug ejection device and proper operation of the user. In such a case, the function of allowing the user to recognize the malfunction of the device including a drug ejection unit, physical mounting mistake of consumables and the like in some manner is preferably included.
Even when the drug ejection unit in the drug ejection device is set normally, the ejected liquid needs to be reliably inhaled by the user.
In order to allow the user to reliably inhale the liquid ejected to the user through the oral cavity or the nasal cavity, the method of taking the inspiration air of the user as negative pressure (air pressure lower than atmospheric pressure) in the inhaling passage, and actuating ejection with the timing of the inspiration as the reference is considered as general ejection actuation method. Namely, when the negative pressure in the inhaling passage exceeds a predetermined value, the drug ejection device determines that the user performs inhalation and starts ejection. However, a portable drug ejection device or the like takes the atmospheric pressure change due to a gust as occurrence of the negative pressure when the gust occurs outdoors, and the ejection actuation unit is likely to operate and eject a liquid at the undesired time. In the ejection device which takes the inhalation intention of the user by the user simply pressing an actuation button or the like, and ejects a liquid, an actuation button or the like can be erroneously pressed to eject a liquid at an undesired time.